Browser-recognizer

A from-microphone speech recognizer built on Vosk that can be run on the browser, inspired by vosk-browser, but built from scratch and no code taken!

Interface

• setLogLevel: set Kaldi's log level (default: -1)
  • -2: Error
  • -1: Warning
  • 0: Info
  • 1: Verbose
  • 2: More verbose
  • 3: Debug

Model and SpkModel

new Model(url, storepath, uid)
new SpkModel(url, storepath, uid)

Functions

• constructor : Construct a model from an URL, storage path, and an UID.
  • If storepath contains valid model files and uid is the same, there will not be a fetch from url
  • If storepath doesn't contain valid model files, or if it contains valid model files, but uid is different, there will be a fetch from url, and the model is stored with uid
• delete: Delete self and free resources

Events

• ready: The model is ready to be put into a recognizer via the constructor for Model, or setSpkModel() for SpkModel
• error: An error occured, check the event's details property for more information

Recognizer

new Recognizer(model)

Functions

• constructor: Construct a recognizer from a model object
• start: Start recognizing
• stop: Stop recognizing
• setWords: Return words' information in a result event (default: false)
• setPartialWords: Return words' information in a partialResult event (default: false)
• setNLSML: Return result and partialResult in NLSML form (default: false)
• setMaxAlternatives: Set the max number of alternatives for result event (default: false)
• setGrm: Add grammar to the recognizer (default: none)
• setSpkModel: Set the speaker model of the recognizer (default: none)

Events

• partialResult: There is a partial recognition result, check the event's details property
• result: There is a full recognition result, check the event's details property
• error: An error occured, check the event's details property for more information delete: Delete self and free resources

Other key points

IMPORTANT

You MUST call delete() on objects at the end of its usage. Or put:

__GenericObj__.objects.forEach(obj => obj.delete())

at the end of your program to automatically do that. We have to do this because Emscripten doesn't call destructors. See here.

Guarantees

If an error occurs (error event is fired), no changes was made, and no other dependent events will fire. For example, if an error occur while loading the model, the "ready" event won't fire in order to prevent executing code on a nonexistent model.

Limitations compared to vosk-browser:

• Only works on main thread
• Microphone only
• Fixed memory size at 300MB, changing it require recompilation

Additions to vosk-browser:

• Multiple models support
• Speaker model (SpkModel) support
• Storage path management (when many models are required)
• Model ID management (when model updates are required)

This requires SharedArrayBuffer, so set the response headers:

• Cross-Origin-Embedder-Policy ---> require-corp
• Cross-Origin-Opener-Policy ---> same-origin

If you can't set these headers, you can use a VERY HACKY workaround at src/addCOI.js.

Usage

<!--Load this from a script tag-->
<script src="BrowserRecognizer.js">